Have a tank with axolotls in it. May share tank nudez soon. Never dealt with parasites before but... if you caught that one... why not just kill it and flush it down the toilet or something?
I'm not a fan of killing fish too much I might setup a quarantine tank with a spare ten gal and try to treat it, not sure though. [EDIT] : some people are saying it's just a growth on it. It should be okay but I'll need to watch it.
Oh. That's a fish. I thought that was the parasite you were talking about. I lost my all of my brain cells 16 years ago, forgive me. Quarantine tank sounds like the way to go.